Every company in France is classified under the APE (activité principale de l'entreprise) scheme. It simply refers to the main activity carried out by your business. The INSEE has established an official list which is regularly updated.
Please note that the APE code does not determine the activities that can be carried out by your company. The document which matters most for this purpose is the incorporation certificate (extrait Kbis) of your company issued by the competent tribunal.
You may need to amend this code, for one of the following reasons: